3D CHIP CRACKSTOP
Embodiments of the present invention provide a crackstop and seal ring for 3D chip stacked wafers. A continuous through-silicon trench (TST) spans multiple wafers of a 3D chip stacked wafer, and forms a closed shape around a functional circuit or die, protecting the chip during subsequent fabrication such as dicing and packaging.
Latest IBM Patents:
- Integration of selector on confined phase change memory
- Method probe with high density electrodes, and a formation thereof
- Thermally activated retractable EMC protection
- Method to manufacture conductive anodic filament-resistant microvias
- Detecting and preventing distributed data exfiltration attacks
The present invention relates generally to semiconductor fabrication, and more particularly, to a crackstop for a 3D stacked chip.
BACKGROUND OF THE INVENTIONThe density of integrated circuit chips has been increasing at a rapid rate over the past decade, and this need for increased density will continue for applications such as mobile phones, digital cameras, global positioning systems (GPS), and computers. In addition, there is a demand for increased chip packaging density to increase performance, reduce space, and provide higher functionality per unit volume needed for applications such as space-based electronic systems, miniaturized electronics for weaponry and surveillance, and hand-held electronics systems. One solution to the demand for increased density is to package the chips closer together, so that the effective density per unit volume increases. The densest packaging of chips is to stack them one on top of another into a single three dimensional (3D) unit or cube. Such a multi-level chip assembly which is also known as a 3D chip, allows a plurality of flash memory chips or a CPU to be stacked with at least one memory chip and other types of chips. With the large number of integrated circuits being produced today, product yield becomes significant. It is therefore desirable to have improvements in the fabrication of 3D chips that can improve product yield.
SUMMARY OF THE INVENTIONIn a first aspect, embodiments of the present invention provide a method of forming a crackstop on a 3D semiconductor structure, the 3D semiconductor structure comprising a first wafer having a substrate and a back-end-of-line (BEOL) region, a second wafer having a substrate and a back-end-of-line (BEOL) region, wherein the second wafer is disposed on the first wafer, the method comprising: forming a through-silicon-trench (TST) in a closed shape around a circuit formed in the 3D semiconductor structure, wherein the TST traverses the second wafer, and extends through the BEOL region of the first wafer, and into the substrate of the first wafer.
In a second aspect, embodiments of the present invention provide a semiconductor structure comprising: a first wafer having a substrate and a back-end-of-line (BEOL) region; a second wafer having a substrate and a back-end-of-line (BEOL) region, wherein the second wafer is disposed on the first wafer; and a through-silicon-trench (TST) formed in a closed shape around a die that is formed in the semiconductor structure, wherein the TST traverses the second wafer, and extends through the BEOL region of the first wafer, and into the substrate of the first wafer.
In a third aspect, embodiments of the present invention provide a semiconductor structure comprising: a first wafer having a substrate and a back-end-of-line (BEOL) region; a second wafer having a substrate and a back-end-of-line (BEOL) region, wherein the second wafer is disposed on the first wafer; a third wafer having a substrate and a back-end-of-line (BEOL) region, wherein the third wafer is disposed on the second wafer; and a first through-silicon-trench (TST) formed in a closed shape around a circuit that is formed in the semiconductor structure, wherein the first TST traverses the third wafer and the second wafer, and extends through the BEOL region of the first wafer, and into the substrate of the first wafer.
The structure, operation, and advantages of the present invention will become further apparent upon consideration of the following description taken in conjunction with the accompanying figures (FIGs.). The figures are intended to be illustrative, not limiting.
Certain elements in some of the figures may be omitted, or illustrated not-to-scale, for illustrative clarity. The cross-sectional views may be in the form of “slices”, or “near-sighted” cross-sectional views, omitting certain background lines which would otherwise be visible in a “true” cross-sectional view, for illustrative clarity.
Often, similar elements may be referred to by similar numbers in various figures (FIGs) of the drawing, in which case typically the last two significant digits may be the same, the most significant digit being the number of the drawing figure (FIG). Furthermore, for clarity, some reference numbers may be omitted in certain drawings.
Embodiments of the present invention provide a crackstop and seal ring for 3D chip stacked wafers. A continuous through-silicon trench (TST) spans multiple wafers of a 3D chip stacked wafer, and forms a closed shape around a functional circuit or die, protecting the chip during subsequent fabrication such as dicing and packaging. Overall, the crackstop provides additional mechanical robustness for the 3D chip.
Although the invention has been shown and described with respect to a certain preferred embodiment or embodiments, certain equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of this specification and the annexed drawings. In particular regard to the various functions performed by the above described components (assemblies, devices, circuits, etc.) the terms (including a reference to a “means”) used to describe such components are intended to correspond, unless otherwise indicated, to any component which performs the specified function of the described component (i.e., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated exemplary embodiments of the invention. In addition, while a particular feature of the invention may have been disclosed with respect to only one of several embodiments, such feature may be combined with one or more features of the other embodiments as may be desired and advantageous for any given or particular application.
Claims
1. A method of forming a crackstop on a 3D semiconductor structure, the 3D semiconductor structure comprising a first wafer having a substrate and a back-end-of-line (BEOL) region, a second wafer having a substrate and a back-end-of-line (BEOL) region, wherein the second wafer is disposed on the first wafer, the method comprising:
- forming a through-silicon-trench (TST) in a closed shape around a circuit formed in the 3D semiconductor structure, wherein the TST traverses the second wafer, and extends through the BEOL region of the first wafer, and partially into the substrate of the first wafer.
2. The method of claim 1, wherein forming a TST comprises forming a TST having an aspect ratio ranging from about 1:10 to about 1:40.
3. The method of claim 1, wherein forming a TST comprises forming a TST having a width ranging from about 7 micrometers to about 30 micrometers.
4. The method of claim 1, wherein forming a TST comprises forming a TST having a depth ranging from about 30 micrometers to about 1000 micrometers.
5. The method of claim 1, wherein forming a TST comprises performing a deep reactive ion etch.
6. The method of claim 5, further comprising forming an oxide liner on interior surfaces of the TST.
7. The method of claim 6, further comprising filling the TST with a metal.
8. The method of claim 7, wherein filling the TST with a metal comprises filling the TST with copper.
9. The method of claim 7, wherein filling the TST with a metal comprises filling the TST with tungsten.
10. The method of claim 7, further comprising planarizing the metal.
11. The method of claim 10, wherein planarizing the metal is performed via a chemical mechanical polish process.
12. A semiconductor structure comprising:
- a first wafer having a substrate and a back-end-of-line (BEOL) region;
- a second wafer having a substrate and a back-end-of-line (BEOL) region, wherein the second wafer is disposed on the first wafer; and
- a through-silicon-trench (TST) formed in a closed shape around a die that is formed in the semiconductor structure, wherein the TST traverses the second wafer, and extends through the BEOL region of the first wafer, and partially into the substrate of the first wafer.
13. The semiconductor structure of claim 12, wherein the TST is formed in a serpentine shape.
14. The semiconductor structure of claim 12, wherein the TST is formed in a zigzag shape.
15. The semiconductor structure of claim 12, wherein the TST has a depth ranging from about 30 micrometers to about 1000 micrometers.
16. The semiconductor structure of claim 12, further comprising an oxide liner disposed on interior surfaces of the TST.
17. The semiconductor structure of claim 12, further comprising a metal fill material disposed within the TST.
18. The semiconductor structure of claim 17, wherein the metal fill material comprises copper.
19. A semiconductor structure comprising:
- a first wafer having a substrate and a back-end-of-line (BEOL) region;
- a second wafer having a substrate and a back-end-of-line (BEOL) region, wherein the second wafer is disposed on the first wafer;
- a third wafer having a substrate and a back-end-of-line (BEOL) region, wherein the third wafer is disposed on the second wafer; and
- a first through-silicon-trench (TST) formed in a closed shape around a circuit that is formed in the semiconductor structure, wherein the first TST traverses the third wafer and the second wafer, and extends through the BEOL region of the first wafer, and partially into the substrate of the first wafer.
20. The semiconductor structure of claim 19, wherein the first wafer, second wafer, and third wafer comprise a first 3D substructure, and further comprising a second 3D sub-structure, wherein the second 3D sub-structure comprises:
- a fourth wafer having a substrate and a back-end-of-line (BEOL) region, wherein the fourth wafer is disposed on the third wafer;
- a fifth wafer having a substrate and a back-end-of-line (BEOL) region, wherein the fifth wafer is disposed on the fourth wafer; and
- a second through-silicon-trench (TST) formed in a closed shape around a die that is formed in the semiconductor structure, wherein the second TST traverses the fifth wafer, and extends into the fourth wafer.
Type: Application
Filed: Sep 12, 2013
Publication Date: Mar 12, 2015
Applicant: International Business Machines Corporation (Armonk, NY)
Inventors: Mukta G. Farooq (Hopewell Junction, NY), Erdem Kaltalioglu (Newburgh, NY)
Application Number: 14/024,663
International Classification: H01L 23/00 (20060101); H01L 23/48 (20060101); H01L 21/768 (20060101);